Steeltec fills a previously vacant space on the material properties map
New HSX® Z10 steel combines strength and ductility
Components used in the automotive industry have to withstand powerful transverse loads and high internal pressures and this places high demands on the strength and ductility of the steels used. If optimum vehicle safety is to be achieved, the material used must be capable of being machined to high precision and the finished component must exhibit long-term dimensionally stability even when subjected to maximum loads. The ideal steel has to fulfil numerous stringent requirements. It must exhibit high dynamic strength and high tensile strength, show good machinability and weldability, and it must be suitable for case hardening. HSX® Z10 – the new high-strength bright steel from Steeltec – fills what was until now an unoccupied space on the material properties map. And there’s more: microalloying means that this new steel is comparatively cost-efficient, as well.
Mobility concepts for today’s world and the continuous advances in the development and manufacture of automotive components are placing increasingly stringent demands on the attributes of high-tech materials. Ultimately, a component is only as good as the material used to make it. The particular combination of physical and mechanical properties that the steel needs to provide can be determined by examining the details of the production process and the loads to which the component will be exposed when in use. By analysing the latest trends in the industry, Steeltec has not only identified current engineering challenges, it has also found a solution: ‘HSX® Z10 is a microalloyed special steel that we have developed to fulfil a unique mix of requirements: good machinability combined with ductility and a high resistance to transverse loads,’ explains Guido Olschewski, Head of management systems and product design at Steeltec – a company within the SCHMOLZ + BICKENBACH Group.
Targeted material development
Steeltec’s new ferrite-pearlite special steel HSX® Z10 is ideally suited for the fabrication of highly stressed parts, such as the drive shafts or pump components used in the automotive, mechanical engineering and hydraulics industries. With a tensile strength of at least 900 MPa, an endurance limit of 400 MPa under a rotating bending load and an elongation after fracture of at least 10 %, HSX® Z10 is a major addition to the company’s portfolio of higher strength HSX® special steels. The key to achieving this particular set of material properties lies in the microalloying elements used. As a result, HSX® Z10 is barely affected by fluctuations in the prices of expensive alloying elements. The material’s outstanding resistance to transverse forces has been achieved principally by reducing the quantity of manganese sulphides in the microstructure. Chemical analysis shows that carbon, which is used to improve hardness, is only present at a concentration of 0.3 percent, which in turn makes HSX® Z10 easy to weld. Microalloying elements like vanadium are used to obtain the required material strength. The materials technologists at Steeltec have also managed to configure HSX® Z10 so that despite its low carbon content it is suitable for case hardening. By subjecting the steel to induction hardening, users have achieved hardness values of 55 HRC.
Like all other steels in the HSX® and ETG® series, HSX® Z10 already possesses a high level of strength in its as-delivered state. This makes it particularly cost-effective to process and results in correspondingly low manufacturing costs. Conventional quenched and tempered steels frequently have to be heat treated after being machined on a lathe. However, this can cause quenching distortion, which then needs to be treated by additional post-processing stages. These additional steps are not necessary if a Steeltec special steel is used and this fact helps to keep the component within the specified design tolerances as well as improving throughput times.
Working together to enhance research and development
‘This new special steel is the result of our expertise in materials technology and in steel production,’ explains Guido Olschewski. ‘Using computational tools as well as databases that store empirical data on our steels, we begin by determining all relevant conditions and constraints.’ The base material is 1.1302 grade steel, which Swiss Steel – a Steeltec affiliate – then combines with the requisite alloying elements in its own steelworks. The fine tuning of the steel’s properties occurs when the stock is processed on the bar drawing bench. Steeltec is able to adjust the materials physical and mechanical properties by carefully controlling the drawing temperature and the true strain in the material. Controlled drawing also ensures that the strength of the material is uniform across the bar’s cross section for all bar sizes in the available dimensional range.
It is standard procedure at Steeltec to work with external research institutes to test the suitability of Steeltec bright bar products for specific applications. In this particular case, the testing campaign involved determining the dynamic strength of HSX® Z10 at the Swiss Federal Laboratories for Materials Science and Technology (Empa) and conducting tests to determining the material’s suitability for high-frequency induction hardening. The Fellbach Welding Institute (GSI SLV Fellbach) in Germany also tested HSX® Z10 and demonstrated the comparatively good weldability of this new special steel, which is currently undergoing the first test applications by Steeltec customers. The results of these application tests will be entered into the Steeltec knowledge bases and represent the final stage in achieving a comprehensive characterisation of the material and its properties. ‘It is one of our principles at Steeltec to gather information on all of the parameters that affect the design and fabrication of components when our steels are processed by our customers,’ says Olschewski. ‘This approach helps us to provide customers with expert advice and to drive up quality across the board.’
HSX® Z10 special steel bar from Steeltec is available in the sizes 4.15 mm to 55 mm via the global sales and services network within the SCHMOLZ + BICKENBACH Group.
Figure 1: HSX® Z10 in the product portfolio, source: Steeltec
Figure 2: HSX® Z10 machining, source: Steeltec
Figure 3: Worm gear shaft, source: Steeltec
Figure 4: Steel production, source: Swiss Steel
Figure 5: Drawing process, source: Steeltec
Figure 6: Special steel HSX® Z10, source: Steeltec
About the Steeltec Group
With a workforce of around 620 in six locations in Denmark, Germany, Sweden, Switzerland and Turkey, the Steeltec Group is one of Europe’s leading manufacturers of special bright steel. Steeltec’s four self-owned production centres fabricate high-strength and higher strength special steel, high-quality bright steel, special quenched and tempered steel, free-cutting steel, case-hardened steel and engineering steel. Core areas of expertise include the application-specific development and production of high-quality bright steel, precision finishing operations and professional technical advice that is provided locally. The Steeltec Group works closely with customers, suppliers and research institutions to continually improve the production and engineering properties of steel, driving competitiveness across the entire value chain. Thanks to its Europe-wide distribution network, Steeltec can guarantee delivery reliability to its customers in the automotive, hydraulic and mechanical engineering industries.
About SCHMOLZ + BICKENBACH
Today, the SCHMOLZ + BICKENBACH Group is one of the world’s leading providers of customised solutions in the specialty steel long products business. A global name in tool steel and stainless long steel, the Group is one of two largest companies in Europe for alloy and high-alloy engineering steel. With around 10 000 employees at its own production and distribution companies in 38 countries across five continents, the Company supports and supplies customers wherever they operate. Besides the comprehensive Production and Sales & Services portfolio, customers benefit from the Company’s technological expertise, consistent high quality worldwide and in-depth knowledge of local markets.
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